Resilient thread.



P. W. PRATT.

RESILIENT TREAD.

APPLICATION FILED MAR. 2s, 1912.

Lge Patented Deo. 23, 1913.

A vf l I a wm hlillQlll.

RESILIENT TREAD To all '1c/wm it may' concern:

Be it known that l', 'P1-mar W. PRATT, a citizen ot' the United States, and a resident oit' Boston, in the county of Sudolk and State of lllassachusetts, have invented certain new afnd' useful Improvements in Resilient Trends, of which the following is a specification.

This invention relates to resilient treads, particularly in the shape of elastic tires for vehicle wheels, although adapted for other purposes such as stair treads, boot and shoe heels and soles, etc.

The object of the invention is to provide an elastic tread having relatively inelastic inserts or plugs, of non-slip ing; character, the plugs being so arranged t at they are operative for the purposes for which they are intended during the entire life of the elastic tread, without detracting materially from the resilience of the tread.

The invention is embodied in a resilient tread comprising a bodyof elastic material having a tread Jface which may be the outer surface of an elastic vehicle tire, and a back tace which may be the inner surface oi the tire bearing on the rigid rim of the wheel, a series of anti-slipping outer plugs extending inwardly from the tread face, partly but y notentirely to the back face, and a, series of similar inner plugs extending outwardly from the inner face partly but not entirely to the outer face and alternating with the outer plugs.

f the accompanying drawings, forming a part of this specilication,-Figure l represents a perspective sectional view of a portion of an elastic tire embodying my invention. Fig. 2 represents a section on line 2-2 of Fig. il.

In the drawings, l2 represents an elastic body which may be composed oi any of the compositions ot which so-called solid rubber tires are usually made. In the outer tace of the body l2 are inserted a series of outer plugs 1.3, the outer ends oi which are iiush with the outerface oi the body l2, while their inner ends are separatedV from the inner face of said body by a considerable part specification of Letters Patent.

Application led harch 23, 1912.

intented Dec. 23, iill.

serial No. 685,891.

considerable thickness of the latter. Each ot' the said plugs is preferably formed by rollingr a sheet of cotton duck, or other suitable textile l'abric, suitably rictioned or treated with unvulcanized rubber in solution, into a solid cylinder. The plugs are inserted, while the rubber therein is unvulcanized, into the unvulcanized body l2, the whole being;` then subjected to vulcanizing heat in a suitable mold orv container. rihe vulcanization oi" the rubber oi the body l2 and plugs 14 causes a firm and intimate union between the body and the plugs and between the convolutions of the fabric of which the plugs are composed;

The first wear on the body l2 is sustained by the outer plugs 13, andnot by the inner plugs lli, there being no wear on the inner plugs until the outer plugs and the body l2 have been worn down to the line www, Fig. 2. luringr this period ot' wear, the outer plugs 13 are cushioned by the elastic mateial between their inner ends and the back racc of the body 1Q. the material between the inner plugs 14 and the outer face of the body l2 being' tree to expand and contract.

When the body 12 has been worn to the eX- tent indicated by Fig. 2, the inner plugs le areexposed and impart an anti-slipping quality to the partially worn tire.

The plugs may be laterally perforated to form recesses or pockets l5. which are filled by the material of which the body l2 is made, these per'orations and fillings rendering the plugs longitudinally compressihle to sonic extent.

The inner plugs i4 should have a -considerable degree of longrillulinal compressi bility or elasticity so that when they are eX- posed by wear, their tread ends will yield inwardly with the .surroumlingl surface of the body l2. Fig. l shows the inner ends of the plugs lll provided with recesses or cups lli for this purpose.

Fig. Q shows the inner plugs provided with a ,Qreater nun'iber oiE recesses or pockets l5 than the outer plugs, these recesses or pockets accomplishing the same purpose as the recesses lit s has been stated, the wear on the body l2 first causes the outer plugs 1.3 to serve their purpose to prevent the body being' worn away. At such time the inner plugs lli are servmg; no purpose, other than to render the body substantially uniform throughout all its parts, so ier as concernsV radial rigidity. By this I mean that, since the plugs of fabric and rubber are necessarily less elastic than the body 12, the presenr-tA of the large number' of plugs 13 and 14 in the body, substantially equally spaced circumierentially, renders the body, as a whole, quite uniform. At the same time,

however, the structure of the body with the l when -Wear' has occurred down to the line -w of Fig. 2, the tire will possess ample anti-slipping quality, even though the small remaining portions of the plugs 13 should drop or be forced out. This could not be the case if the plugs of the diiierent series did not overlap each other in the manner described.

The construction is such that there will be a continuous fiber surface presented as the body wears, and yet it avoids the rigidity `that would result from extending the plugs all the way through from the tread to the inner face of the body 12.

I claim 1. .A resilient tread comprising a body of elastic material and a plurality of series of anti-slipping plugs of fabric embedded in said body, the plugs of one series extending inwardly from the tread face of said body but not throughA to the back face, the plugs of the next series alternating with and overlapping the inner ends of the plugs of the first-mentioned series but not extending to tire outer or tread face, whereby the cont-inuity of the function of the plugs'will be preserved durin wear without impart-ing uidue radial rigidity by the employment of p 2.1gA resilient tread comprising a body of elastic material having a tread face and a back face, a series of anti-slipping outer plugs extending inwardly from the tread face partly but not entirely to the back face, and a series of similar inner plugs extend-v ing outwardly from the inner face partly but not entirely to the outer face, and alternating with the outer plugs, said plugs having lateral recesses to render them longitudinally compressible.

3. A resilient tread comprising a body of elastic material having a tread face' and a back face, a series of anti-slipping outer plugs extending inwardly from the tread face partly but notentircly to the back face, and a series of similar inner plugs extending outwardly from the inner face/partly but not entirely to the outer face, and alternating with the outer plugs, said plugs naving lateral recesses to render them longitudinally compressilole, the inner plugs being provided with a` greater number of said recesses than the outer plugs to render said irner plugs more compressible than the outer u s. Y p Igii testimony whereofk I have axed my signature, in presence of two Witnesses.

PHILIP W. PRATT.

Witnesses:

C. F. BROWN, H. L. ROBBINS. 

